A volumetric sampler designed to facilitate capillary drainage.

Abstract

The present invention relates to a volumetric sampling device assembly (30), comprising a tip (16) and an ejector (20), the tip (16) comprising a body (42), a movable capillary retaining portion (44) connected to the body by a connector, and a lever (54) fixed to the movable portion, such that radially inward movement of the portion via the connector leads to radially outward movement of the lever (54), the ejector (20) comprising a locking member (64) engaging with the lever (54), the locking member (64) assuming a locking position in a top position of the ejector (20) which holds the movable capillary retaining portion (44) in an active capillary retaining position by preventing the lever (54) from moving radially outward, and during the ejection movement the locking member (64) allowing the lever (54) to move radially outward.

Description

[Technical field]

[0001] The present invention relates to the field of volumetric sampling devices, for example sampling pipettes, also called laboratory pipettes or liquid transfer pipettes, which are intended for sampling and dispensing liquids in containers etc. The present invention also relates to a volumetric sampling device in programmable controller form. [Background technology]

[0002] As regards manual single-channel or multichannel pipettes, they are intended to be held by the operator during liquid sampling and dispensing operations, which are performed by applying axial pressure to a control button, which is actuated by this button. As regards so-called positive displacement pipettes, they are intended to cooperate with consumables of the plunger-capillary system type, and a piston is provided which is in direct contact with the specimen to be sampled before ejection or reuse. Positive displacement pipettes therefore have a different design from that of conventional air-displacement pipettes, in which the piston is an integral part of the pipette and is not in direct contact with the specimen.

[0003] In a known manner, a capillary is intended to be attached to the tip of a pipette. The retention of the capillary to the tip must be sufficiently firm to ensure that the capillary does not detach during pipetting, in particular during dispensing, regardless of the viscosity of the liquid.

[0004] These requirements necessitate secure axial attachment of the capillary to the tip of the pipette, with the result that capillary ejection becomes increasingly difficult as the attachment force increases.

[0005] This conflicting situation creates ergonomic problems for plunger-capillary system ejection: in fact, the operator must exert a significant force to achieve the desired ejection using the ejector integrated in the pipette, which can result in comfort issues as well as the development of repetitive strain injury (RSI). Summary of the Invention [Problem to be solved by the invention]

[0006] Similar problems arise in devices such as programmable controllers that implement motorized ejection of plunger-capillary systems because the ejection motor must be large enough to withstand the force of the capillary attachment to the tip in order to break the mechanical connection between the tip and the capillary. We note that these problems are exacerbated in multichannel designs. [Means for solving the problem]

[0007] To address this problem, the present invention is directed to a positive displacement device assembly, the assembly comprising: a tip intended to support a capillary of a plunger-capillary system, the tip being hollow and centered about a longitudinal central axis of the tip and including an outer surface providing an axial retention for the capillary; an ejector intended to eject a plunger-capillary system, the assembly being designed to allow an axial ejection movement of the ejector relative to the tip between an upper rest end position and a bottom ejection end position, the ejector including an ejection end that is in axial contact with the capillary end during the ejection movement; Equipped with.

[0008] According to the invention, the tip includes a body and a movable capillary holding part connected to the body by a link, the movable holding part including at least a part of the axial holding member of the capillary on its outer surface, the tip also includes a lever rigidly connected to the movable holding part, whereby radially inward tilting of the movable part relative to the tip body via the link actuates radially outward tilting of the lever, The ejector includes a locking member that cooperates with the lever, whereby In the upper rest end position of the ejector, the locking member occupies a locking position which prevents the lever from tilting radially outward, thereby holding the movable part of the tip in the active holding position of the capillary tube; During the ejection movement of the ejector, the locking member allowing radially outward tilt of the lever resulting from radially inward tilt of the movable part from its active retention position of the capillary tube to its retraction release position; or A radially outward tilt of the lever is actuated which causes a radially inward tilt of the movable portion from its actively retaining position of the capillary tube to its retraction release position of the capillary tube.

[0009] Therefore, the present invention provides for tip functionalization by adopting a segmented / slotted design that allows to fully deal with the above conflicting situations. Indeed, the present invention allows a movable holding part supported by the tip to be held in an active holding position of the capillary during pipetting, thereby ensuring a secure attachment of this capillary to the tip. Furthermore, the movable holding part can be retracted to its retracted release position of the capillary, thereby considerably limiting the force that must be exerted on the ejector to trigger the detachment and ejection of the plunger-capillary system.

[0010] It is finally emphasized that the present invention also allows offsetting of the ejection function to a secondary system, whereas in existing systems the ejection control largely overlaps with the pipetting control and therefore generates significant forces.

[0011] The present invention preferably comprises at least one of the following optional features taken alone or in combination.

[0012] Preferably, in the tip, the link between the movable capillary holding portion and the tip body is a flexible, resiliently deformable link.

[0013] Preferably, the tip includes an intermediate ring centered on its longitudinal central axis, the flexible link being made by two flexible zones of thin wall defining between them a first angular ring sector as well as a second angular ring sector, the first angular sector being connected to the movable capillary holding part and the lever and disposed between the two, whereas the second angular sector is rigidly connected to the tip body.

[0014] Preferably, the two flexible zones of reduced thickness are diametrically opposed.Preferably, the tip also includes a fastening plate rigidly connected to the second angular ring sector.

[0015] Preferably, the tip is made in one piece, although alternatively the design of several parts assembled together can be devised without departing from the scope of the invention. Preferably, the locking member provided on the ejector is embodied by a radial stop member intended to cooperate with an inclined surface of the tip lever.

[0016] According to an alternative to the flexible link described above, the link between the movable capillary holding portion and the tip body can be a pivot link or a ball joint link. Preferably, the movable capillary holding portion has a substantially semi-cylindrical shape. Preferably, another part of the axial holding member of the capillary is provided on the outer surface of the tip body.

[0017] In this regard, it is noted that the axial retention of the capillary tube is preferably embodied using at least one annular bead on the outer surface of the tip.

[0018] Preferably, regardless of the design chosen for the link between the movable holding portion and the tip body, the movable capillary holding portion and the tip lever are made integrally.

[0019] The invention also relates to a positive displacement device comprising at least one such assembly, for example a single or multi-channel manual or motorized positive displacement sampling pipette or a single or multi-channel programmable positive displacement sampling controller.

[0020] Further advantages and features of the present invention will become apparent in the following non-limiting detailed description. [Brief description of the drawings]

[0021] Reference is now made to the accompanying drawings, in which: [Figure 1]1 illustrates a perspective view of a positive displacement sampling pipette according to the present invention; [Diagram 2] FIG. 2 shows a partial longitudinal section of the pipette shown in the previous figure, in particular showing an assembly according to a first preferred embodiment of the invention; [Diagram 3] FIG. 2 shows a perspective view of a pipette tip belonging to the assembly shown in the previous figure. [Figure 4] FIG. 2 illustrates a side view of the tip shown in the previous figure. [Diagram 5] Figure 3 represents a partial longitudinal section similar to that in Figure 2, showing the plunger-capillary system assembly at a given point during ejection operation. [Figure 6] 6 represents a perspective view of the tip in the state adopted at the given time represented in FIG. 5. [Figure 7] 6 shows a partial longitudinal section similar to FIG. 5 of the plunger-capillary system at the end of the ejection operation. [Figure 8] FIG. 4 shows a side view of an assembly according to a second embodiment of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] 1, there is shown a manually operated single channel positive displacement pipette 1 according to the present invention. This manual pipette is also called a "mechanical pipette." Throughout the following description, the terms "top" and "bottom" shall be considered with respect to the pipette held upright at or near the pipette operating position.

[0023] In Figure 1, the pipette 1 is shown held in the hand 2 of an operator using his thumb 4 to actuate the pipette so as to cause the dispensing of a liquid already aspirated. More specifically, the pipette 1 comprises a handle 6 forming the upper body of the pipette, from which extends a pipette operation control rod 10. This rod supports at its upper end in the pipette operating position a control button 12, the upper part of which is intended to be pressed by the operator's thumb 4.

[0024] It is noted that, if necessary, the handle 6 may be provided with a display screen (not shown). Similarly, means are available to the operator at this handle 6 for setting the volume to be sampled.

[0025] Beneath the handle 6, the pipette 1 comprises a removable base 14 and its outer base body 15. The base 15 terminates at the bottom in a tip 16 which receives a consumable 18 called the plunger-capillary system. Only the capillary 21 of the system 18 can be seen in Fig. 1, since the plunger is located inside the capillary 21 and the tip 16. In a known manner, the plunger-capillary system 18 can be mechanically ejected after pipetting by an ejector 20, whose actuating button 22 is located protruding beyond the top of the handle, for example in the vicinity of the control button 12.

[0026] The pipette action control rod 10 is connected at its bottom end to a gripping system (not shown in FIG. 1) and is capable of gripping and releasing the plunger of the plunger-capillary system 18 by well-known techniques not described here.

[0027] 2 to 4, there is shown an assembly 30 according to a first preferred embodiment of the present invention, which is integrated into the pipette shown in FIG. 1 and which includes the entire tip 16 and ejector 20 of a particular design. The tip 16, which is best seen in FIGS. 3 and 4, has a hollow shape centered about a central longitudinal axis 32 of the tip, which corresponds here to the central longitudinal axis of the single channel pipette. The hollow of the tip 16 is intended to receive the plunger 23 of the plunger-capillary system 18, the upper end of which is gripped by a gripping system 34 actuated by a pipette movement control rod.

[0028] The outer surface 36 of the tip 16 is provided with a capillary axial retention member 38 embodied in the form of an annular bead, shoulder or similar form centered on the axis 32. In either case, the member 38 forms an axial stop intended to retain the capillary tube 21 in the tip 16. In a known manner, the inner surface of the upper part of the capillary is shaped to cooperate with the tip axial retention member 38, for example by providing an annular projection 40 extending radially inwards and received in a tip recess 41 defined at its base by the member 38.

[0029] More specifically, because the outer surface 36 of the tip has a segmented / slotted design unique to the present invention, as will be described below, the capillary axial retention member 38 does not extend continuously around this outer surface, and thus the member 38 has the same circumferential segmented / slotted design.

[0030] The main part of the tip 16 is not actually completely cylindrical, since a segmentation is made between the tip body 42 and the movable capillary holding portion 44. The tip body 42 is fixed and has a generally semi-cylindrical shape at its top 42a, whereas the bottom 42b has a generally cylindrical overall shape, the two parts being disposed axially alongside one another and preferably being made in one piece, i.e. integral or not segmented. The material used is preferably plastic or, for example, over-clad aluminium.

[0031] The hollow portion of tip body 42 facing upper portion 42a is occupied by a movable retaining portion 44, which is preferably also generally semi-cylindrical in shape. Together tip body 42 and movable retaining portion 44 form a conventional tip, except that a space 46 separates them circumferentially and axially, resulting in the segmented / slotted design referenced above.

[0032] The bead or shoulder 38 is located partially on the outer surface of the tip body 42 and partially on the outer surface of the movable retaining portion 44 .

[0033] The two elements 42 , 44 which together therefore form the majority of a cylinder centred on the axis 32 are connected to one another at their upper ends by means of an intermediate ring 50 which is also centred on the axis 32 .

[0034] In this ring 50, a flexible link between the tip body 42 and the movable retaining portion 44 is incorporated in the form of two diametrically opposed thin-walled flexible zones 52. Between these two flexible zones 52, a first angular ring sector 50a is initially defined, which is rigidly connected to the movable retaining portion 44, and an opposite second angular ring sector 50b is rigidly connected to the tip body 42. The flexible link allows, as a whole, a pivotal movement of the two angular ring sectors 50a, 50b relative to one another along a transverse pivot axis passing through these two flexible zones 52, due to elastic deformation of the two flexible zones 52.

[0035] Here again, the intermediate ring 50 is made in one piece including the tip elements 42,44.

[0036] Alongside the top of the movable retainer 44, the tip is completed by a lever 54 from a first angular ring sector 50a. The first angular ring sector 50a is thus arranged between the movable part 44 and the lever 54 along the direction of the axis 32. The elements 44, 50a, 54 are thus preferably made in one piece and form a rigid connection assembly that is intended to be substantially undeformed when the pipette is used. On the other hand, to perform the operations described below, a certain rigidity is required in order to ensure that this assembly can be moved in such a way that it is not deformed, in particular that the radial inward tilt of the movable retainer 44 relative to the tip body 42 via the links 52, 52 activates the radial outward tilt of the lever 54.

[0037] Finally, the tip 16 is completed by a fastening plate 56 extending upwards from the second angular ring sector 50b. The plate 56, arranged diametrically opposite the lever 54, forms the fixing part of the tip intended to be fastened directly or indirectly to the outer body 15 of the bottom pipette part.

[0038] As seen in Fig. 2, the ejector 20 is intended to eject the plunger-capillary system 18 by axial pressure on the upper end of the capillary tube 21. The pipette allows an axial ejection movement of the ejector 20 relative to the tip 16 between an upper rest end position shown in Fig. 2 and a bottom ejection end position shown in Fig. 7 and described below. To do this, the ejector 20 comprises a bottom ejection end 60 intended to be in axial contact with the upper capillary end during the ejection movement. In a known manner, the bottom ejection end 60 of the ejector about the axis 32 may have a wide circumferential extent, for example more than 180°.

[0039] The ejector 20 and lever 54 are intended to cooperate together to maintain a secure attachment of the capillary tube 21 to the tip 16 during pipetting, while making it possible to limit the force exerted by the ejector 20 to effect ejection of the plunger-capillary system 18.

[0040] Thus, the lever 54 has a radially outer camming surface 62 at its upper end, the shape of which is such that this surface 62 diverges radially upwards from the axis 32. The camming surface 62 may therefore be an inclined surface or alternatively a curved surface.

[0041] Also, for cooperating with the cam surface 62 of the lever 54, the ejector 20 is provided with a locking member 64, which here corresponds to an axial stop member. As shown in Fig. 2, in the upper rest end position of the ejector 20, the locking member 64 occupies a locking position in which it is placed in contact with the cam surface 62 while being disposed radially outwardly therewith. The locking member 64 thus serves to prevent the lever 54 from tilting radially outwardly and thus to hold the lever in a straight position, thus maintaining the movable holding part 44 in the active holding position of the capillary tube.

[0042] 2, the active holding position of the mobile part 44 also corresponds to a linear position of this mobile part 44 which barely reconstitutes a cylinder together with the fixed tip body 42. In other words, in this active holding position, the part of the bead 38 located on the outer surface of the mobile part 44 is located in its most eccentric position with respect to the axis 32, which makes it possible to help hold the capillary tube 21 securely at the tip. Locking the mobile part 44 in this position by the radial pressure between the elements 62, 64 allows pipetting without the risk of breaking the link between the tip and the capillary tube.

[0043] After pipetting, when the ejection movement is initiated, the ejector 20 is moved downwards and rapidly comes into contact with the upper end of the capillary tube 21, which detaches from the tip 16. In this regard, it is mentioned that at this stage the plunger 23 is released from the gripping system in a known manner, which will not be described here.

[0044] While the bottom discharge end 60 of the ejector 20 presses against the upper end of the capillary tube 21, the ejector, in its downward movement, actuates a stop member 64 in the form of a boss, slug, or other relief feature by which the desired radial stop can be formed.

[0045] A downward movement of the locking member 64 along the cam surface 62 then occurs, allowing the lever 54 to be tilted radially outwardly due to the shape of the ramp. The tilting of the lever 54 results from a radially outward tilt of the mobile part 44, itself caused by the pressure of the capillary tube 21 on a portion of the bead 38 on the surface of the mobile part 44. This situation is made possible by the elastic deformation of the flexible links 52, 52 and the unlocking of the lever 54, as illustrated in Figures 5 and 6, which show the assembly at an intermediate stage during the ejection movement, when the mobile part 44 is pressed radially inwardly so that the capillary tube 21 assumes the retracted and released position.

[0046] 7 shows the situation at the end of the ejection movement, when the bottom ejection end 60 of the ejector in the bottom ejection end position has moved the capillary tube 21 sufficiently so that it is no longer in contact with the outer surface of the tip 16. At this stage, the movable holding part 44 has returned to its straight position due to the fact that it is no longer compressed by the capillary tube 21 and under the action of the elastic return force generated by the flexible zone 52 of the link. When the ejector 20 is released by the operator and returns to its upper rest end position under the action of the spring, the locking member 64 regains contact with the tilting lever cam surface 62, resulting in locking it as in FIG.

[0047] It is necessary to mention that the initial positioning of the capillary tube 21 in the tip 16 is performed in a classical conventional manner by forcing the pipette vertically downwards. The capillary tube 21 is then gripped thanks to a slight elastic deformation of the movable holding part 44 until the desired cooperation between the tip bead 38 and the capillary projection 40 is reached. During this gripping operation of the capillary tube 21, the lever 54 remains immobile in its locking position.

[0048] 8 represents a second preferred embodiment of the invention, in which the flexible zone 52 is replaced by a pivot or ball joint link 66, taking the form of two half links with a joint between the two intermediate ring sectors 50a, 50b. The pivot link 66, with its axis passing through the two half links, is manufactured in a conventional manner, for example using a shaft, a clevis, etc. The link 66 may be provided with elastic return means for urging the movable retaining part 44 towards its active retaining position of the capillary tube. Alternatively, the position of the movable retaining part 44 may be determined by the relative position of the locking member 64 of the ejector in the inclined groove 62' formed in the lever 54.

[0049] During the ejection movement, the slug or roll form of the locking member 64, as it moves in the groove 62', actuates the radial outward tilt of the lever 54, which then leads to the radial inward tilt of the movable part 44 from the active holding position of the capillary tube 21 to the capillary tube retraction release position.

[0050] Various modifications to the invention described above, merely as a non-limiting example, may be made by those skilled in the art, the scope of which is defined by the appended claims. In particular, the preferred embodiment described above corresponds to the implementation of the invention in a manual or single channel pipette, but all teachings may be applied to other types of pipettes, electronic and / or multi-channel, or programmable controllers. [Explanation of symbols]

[0051] 1 Pipette 2 Hands 4 Thumbs 6 Handle 10 Pipette movement control rod 12 Control Buttons 14 Bottom 15 Outer bottom body 16 Tip 18 Plunger-Capillary System 20 Ejector 21 Capillary 22 Operation button 30 Positive Displacement Device Assembly 32 Vertical center axis 34 Grasping System 36 Outer surface 38 Axial retaining member 40 Annular protrusion 41 Recess 42 Tip body 42a Upper 42b bottom 44 Movable capillary holding part 46 Space 50 Rings 50a 1st Angle Ring Sector 50b Second Angle Ring Sector 52 Flexibility Zone 54 Lever 56 Fastening plate 60 Bottom discharge end 62 Slope 62' inclined groove 64 Locking member 66 Pivot / ball joint link

Claims

1. A positive displacement device assembly (30), said positive displacement device assembly comprising: A tip (16) intended to support a capillary (21) of a plunger capillary system (18), said tip being hollow and having an outer surface (36) centered on a longitudinal central axis (32) of said tip and comprising an axial holding member (38) of said capillary; An ejector (20) intended to discharge said plunger capillary system (18), said positive displacement device assembly being designed to enable an axial discharge movement of said ejector (20) relative to said tip (16) between an upper rest end position and a bottom discharge end position, said ejector (20) comprising a discharge end (60) intended to be in axial contact with a capillary end (21) during said axial discharge movement; Comprising Said tip (16) includes, together with a tip body (42), a movable capillary holding portion (44) connected to said tip body (42) by links (52, 52, 66), said movable capillary holding portion (44) including at least a part of said axial holding member (38) of said capillary on its outer surface; Said tip also includes a lever (54) rigidly connected to said movable capillary holding portion (44), whereby a radially inward inclination of said movable capillary holding portion (44) relative to said tip body (42) via said links (52, 52, 66) actuates a radially outward inclination of said lever (54); Said ejector (20) comprises a locking member (64) cooperating with said lever (54); In said upper rest end position of said ejector (20), said locking member (64) occupies a locking position that holds said movable capillary holding portion (44) of said tip in an active holding position of said capillary by preventing a radially outward inclination of said lever (54); During said axial discharge movement of said ejector (20), said locking member (64) Allows, or Actuates, a radially outward inclination of said lever (54) resulting from a radially inward inclination of said movable capillary holding portion (44) of said capillary from its active holding position to its retraction release position of said capillary, a positive displacement device assembly.

2. In the tip part (16), the link (52, 52) between the movable capillary holding part (44) of the capillary and the tip part body (42) is a flexible and elastically deformable link, according to the positive displacement device assembly of claim 1.

3. The tip part (16) includes an intermediate ring (50) centered on the longitudinal central axis line (32), and the flexible link is made by two thin flexible zones (52, 52). Between the flexible zones, a second angular ring sector (50b) is defined together with a first angular ring sector (50a). The first angular ring sector (50a) is rigidly connected to the movable capillary holding part (44) of the capillary and the lever (54) and is arranged between these two, while the second angular ring sector (50b) is rigidly connected to the tip part body (42), according to the positive displacement device assembly of claim 2.

4. The two thin flexible zones (52, 52) are diametrically opposed, according to the positive displacement device assembly of claim 3.

5. The tip part (16) further includes a fastening plate (56) rigidly connected to the second angular ring sector (50b), according to the positive displacement device assembly of claim 3 or 4.

6. The tip part (16) is integrally manufactured, according to the positive displacement device assembly of any one of claims 2 to 4.

7. The locking member (64) provided on the ejector (20) is embodied by a radial stop member intended to cooperate with the inclined surface (62) of the lever (54), according to the positive displacement device assembly of any one of claims 2 to 4.

8. In the tip part (16), the link between the movable capillary holding part (44) and the tip part body (42) is a pivot link (66) or a ball joint link, according to the positive displacement device assembly of claim 1.

9. The movable capillary holding part (44) has a substantially semi-cylindrical shape, according to the positive displacement device assembly of any one of claims 1 to 4.

10. Another part of the axial holding member (38) of the capillary is provided on the outer surface of the tip part body (42), according to the positive displacement device assembly of any one of claims 1 to 4.

11. The axial holding member (38) of the capillary tube is embodied using at least one annular bead on the outer surface (36) of the tip portion (16), the positive displacement device assembly according to any one of claims 1 to 4.

12. The positive displacement device assembly according to any one of claims 1 to 4, wherein the movable capillary holding portion (44) and the lever (54) are integrally manufactured.

13. A positive displacement sample collection device (1) comprising the positive displacement device assembly (30) according to any one of claims 1 to 4.

14. The positive displacement sample collection device (1) according to claim 13, which is a single-channel or multi-channel manual or electric positive displacement sample collection pipette.

15. The positive displacement sample collection device (1) according to claim 13, which is a single-channel or multi-channel manual or electric positive displacement sample collection programmable controller.

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